1. Field of the Invention
The invention relates to a cable drum having a winder which is rotatably mounted on the frame and which has a socket outlet mounted on it.
2. Description of the Related Art
Internal vibrators are often used on building sites in order to compact concrete. The internal vibrators are typically driven by asynchronous motors supplied with a special voltage and a special frequency. If, for example, an asynchronous motor present in the internal vibrator and having an attached unbalanced mass is to achieve a rotational speed of 12,000 rev/min, an excitation frequency of 200 Hz is required in the case of a 2-pole machine. The public power network, however, only provides a frequency of 50 Hz.
For this reason, frequency converters which were usually supplied with three-phase current to couple the motor to the public power network were used in the past. FIG. 2 shows an example of such an arrangement. These frequency converters were very difficult to handle on account of their high weight.
According to FIG. 2, an internal vibrator 1 is connected to a conventional frequency converter 4 via a switch 2 and a cable 3. Since, on building sites, greater distances usually have to be bridged between the working location and the nearest fixed mains connection, the frequency converter 4 is connected to a generally known cable drum 5. A cable 6 can be unwound from the cable drum 5 and connected to the mains connection, which is a long way off.
In recent times, due to the provision of appropriate power electronics with corresponding semiconductors, it has become possible to miniaturize the frequency converter and, in this way, reduce its weight from, for example, 60 kg to 4 kg. Such a lighter frequency converter is still connected between the internal vibrator 1 and the cable drum 5 as a separate unit. When the internal vibrator is moved to different working locations, the frequency converter and the separate cable drum must therefore still be moved.
A cable drum having an integrated light source is described in DE-GM 7641166.